According to the latest Gallup poll 50% of Americans support full legalization of marijuana and only 46% are against this. The response to the first round of petitions regarding legalization has been simply to say "no legalization". In a democratic country when the majority feel this is a worthy issue to debate simply saying "No" is unacceptable.
The fact of the matter is that the prohibition of marijuana only creates and exacerbates issues related to consumption. We learned this lesson with alcohol and ended that prohibition, this resulted in a huge drop in organized crime organized around the illegal alcohol trade. As marijuana is a far safer substance than alcohol should make this an easy choice. While legalization would not solve all issues it would be a much better solution.